This invention relates generally to cargo containers, and more particularly relates to a method for making lightweight laminated panels for cargo containers for aircraft or seagoing vessels.
An aircraft cargo container, also known as a Unit Load Device (ULD), is indispensable in commercial wide body aircraft operation. A wide body airliner typically may carry from six to sixteen aircraft cargo containers every flight. Since fuel expense is one of the major operating costs of operation of airlines, the weight of such aircraft cargo containers has a significant financial impact. Consequently, makers of aircraft cargo containers have been striving to build containers as light as practically possible. An aircraft cargo container typically includes a pallet, a metal frame, a number of body panels and a door. The weight of the body panels accounts for a significant portion of the tare weight of an aircraft cargo container. Therefore, minimizing the weight of panel materials can generate considerable cost savings for air carriers.
The body panels of an aircraft cargo container ideally should be sufficiently stiff so that the container would not deform too much to breach the permissible envelope and cause interference with and damage to an aircraft structure, should have high impact and puncture resistance, should have good protection against water, and should have good resistance to UV and common chemicals encountered in the operational environment of commercial airports. The surface of the body panels also should be easy to bond with logos, decals and repair patches. Material from which such body panels are constructed ideally should have high strength, be lightweight, be of low cost, and should have adequate fire resistance that meets the pertinent FAA requirements as detailed in 14 CFR, part 25, Appendix F.
The latest trend has been to make aircraft cargo container panels out of composite materials. One approach has been to laminate high performance soft fabric, such as para-aramid fabric available under the trademark KEVLAR from E. I. du Pont de Nemours and Company or under the trademark TWARON from Teijin Aramid BV, or ultra high molecular weight polyethylene (UHMW PE) available under the brand name SPECTRA from Honeywell, or under the trademark DYNEEMA from DSM of the Netherlands, for example, with surface protective films such polyolefin, polyurethane or nylon films. Because the surface of para-aramid or UHMW PE fabric is quite difficult to bond with most of the aforementioned protective films, lamination of the material presents many significant challenges. Employing too much heat during lamination may cause the protective film to thin excessively thus exposing the underlying fabric, compromising the UV resistance, or causing undesirable discoloration. Applying too much pressure during lamination may produce strong print-through of fabric on the film surface, making it difficult to bond logos, decals or repair patches to the outer protective film. Applying too little heat on the other hand generally results in poor adhesion between the fabric and the protective films and consequently unsatisfactory durability. It would be desirable to provide a process for reliably making satisfactory lightweight, laminated aircraft cargo container body panel material for use in construction of panels for cargo containers. The present invention meets these and other needs.